When recording a gradation pixel by performing pseudo-halftone processing, the occurrence of unevenness in the density in the recorded image is suppressed. For that purpose, when recording a pseudo-halftone image using dot patterns, a dot-pattern table storing a plurality of different dot patterns is provided for each gradation value. One dot-pattern table is selected from N dot-pattern tables based on gradation-value information for each pixel. One dot pattern is selected from the selected dot-pattern table, based on position information indicated by the pixel, and recording is performed using the selected dot pattern. It is thereby possible to prevent the concentrated use of a particular nozzle of a recording head, and suppress the occurrence of unevenness in the density due to characteristics of the specific nozzle.
Legal claims defining the scope of protection, as filed with the USPTO.
1. An image recording apparatus for performing recording using a dot pattern corresponding to each gradation value, based on image data representing each pixel by one of N gradation values, said apparatus comprising: selection means for selecting one dot pattern based on gradation-value information of the pixel of the image data and position information of the pixel, from a dot-pattern-table storage unit for storing X (N>X, X is a natural number) dot pattern tables, each having a plurality of different dot patterns, corresponding to respective ones of X gradation values; and dot-pattern generation means for generating dot patterns corresponding to (N−X) predetermined gradation values, wherein, when a dot-pattern table corresponding to the gradation-value information is stored in the dot-pattern-table storage unit, the dot pattern selected by said selection means is recorded by a recording head, and wherein, when a dot-pattern table corresponding to the gradation-value information is not stored in the dot-pattern-table storage unit, dot patterns corresponding to the predetermined gradation values generated by said dot-pattern generation means are recorded by the recording head.
2. An image recording apparatus according to claim 1 , wherein the dot pattern generated by said dot-pattern generation means is a dot pattern having a fixed dot arrangement.
3. An image recording apparatus according to claim 2 , wherein the dot pattern generated by said dot-pattern generation means is a dot pattern in which no dot is recorded on all dot positions.
4. An image recording apparatus according to claim 2 , wherein the dot pattern generated by said dot-pattern generation means is a dot pattern in which dots are recorded on all dot positions.
5. An image recording apparatus for performing recording using a dot pattern corresponding to each gradation value, based on image data representing each pixel by one of N gradation values, said apparatus comprising: a dot-pattern-table storage unit for storing X (N>X, X is a natural number) dot-pattern tables, each having a plurality of different dot patterns, corresponding to respective ones of X gradation values; first selection means for selecting one dot pattern from said dot-pattern-table storage unit, based on gradation-value information of the pixel of the image data and position information of the pixel; a second selection means for selecting one dot pattern from the dot-pattern table selected by said first selection means, based on position information of the pixel; and dot-pattern generation means for generating dot patterns corresponding to (N−X) predetermined gradation values, wherein the dot-pattern table is a two-dimensional table expanding in a first direction corresponding to a direction of arrangement of nozzles of the recording head and in a second direction different from the first direction, wherein a number of cells L within the dot-pattern table in the first direction and a number of nozzles A of the recording head have a relationship of L=∝×A (∝ is a natural number), wherein, when a dot-pattern table corresponding to the gradation-value information is stored in said dot-pattern-table storage unit, the dot pattern selected by said second selection means is recorded by a recording head, and wherein, when a dot-pattern table corresponding to the gradation-value information is not stored in said dot-pattern-table storage unit, the dot patterns corresponding to the predetermined gradation values generated by said dot-pattern generation means are recorded by the recording head.
6. An image recording apparatus for performing recording using a dot pattern corresponding to each gradation value, based on image data representing each pixel with one of N (N is an integer equal to or larger than 3) gradation values, said apparatus comprising: a dot-pattern-table storage unit for storing X (N>X, X is a natural number) dot-pattern tables, each having a plurality of different dot patterns, corresponding to X gradation values provided at intervals of every other gradation level; first selection means for selecting one dot-pattern table from said dot-pattern-table storage unit, based on gradation-value information of the pixel of the image data and position information of the pixel; second selection means for selecting one dot pattern based on position information of the pixel, from the dot-pattern table selected by said first selection means; and dot-pattern interpolation means for generating dot patterns corresponding to (N−X) predetermined gradation values, based on a dot pattern within the dot-pattern table corresponding to a gradation value larger than a corresponding one of the predetermined gradation values by one, and a dot pattern within the dot-pattern table corresponding to a gradation value smaller than the corresponding one of the predetermined gradation values by one, wherein the dot-pattern table is a two-dimensional table expanding in a first direction corresponding to a direction of arrangement of nozzles of the recording head and in a second direction different from the first direction, wherein a number of cells L within the dot-pattern table in the first direction and a number of nozzles A of the recording head have a relationship of L=∝×A (≢ is a natural number), wherein, when a dot-pattern table corresponding to the gradation-value information is stored in said dot-pattern-table storage unit, the dot pattern selected by said second selection means is recorded by a recording head, and wherein, when a dot-pattern table corresponding to the gradation-value information is not stored in said dot-pattern-table storage unit, the dot patterns corresponding to the predetermined gradation values generated by said dot-pattern interpolation means are recorded by the recording head.
7. An image recording method for performing recording using a dot pattern corresponding to each gradation value, based on image data representing each pixel by one of N gradation values, said method comprising the steps of: a selection step for selecting one dot pattern based on gradation-value information of the pixel of the image data and position information of the pixel, from a dot-pattern-table storage unit for storing X (N>X, X is a natural number) dot pattern tables, each having a plurality of different dot patterns, corresponding to respective ones of X gradation values, and a dot-pattern generation step for generating dot patterns corresponding to (N−X) predetermined gradation values, wherein, when a dot-pattern table corresponding to the gradation-value information is stored in the dot-pattern-table storage unit, the dot pattern selected in said selection step is recorded by a recording head, and wherein, when a dot-pattern table corresponding to the gradation-value information is not stored in the dot-pattern-table storage unit, the dot patterns corresponding to the predetermined gradation values generated in said dot-pattern generation step are recorded by the recording head.
8. An image recording method for performing recording using a dot pattern corresponding to each gradation value, based on image data representing each pixel by one of N gradation values, said method comprising the steps of: a first selection step for selecting one dot pattern based on gradation-value information of the pixel of the image data and position information of the pixel, from a dot-pattern-table storage unit for storing X (N>X, X is a natural number) dot pattern tables, each having a plurality of different dot patterns, corresponding to respective ones of X gradation value; a second selection step for selecting one dot pattern from the dot-pattern table selected in said first selection step, based on position information of the pixel; and a dot-pattern generation step for generating dot patterns corresponding to (N−X) predetermined gradation values, wherein the dot-pattern table is a two-dimensional table expanding in a first direction corresponding to a direction of arrangement of nozzles of the recording head and in a second direction different from the first direction, wherein a number of cells L within the dot-pattern table in the first direction and a number of nozzles A of the recording head have a relationship of L=∝×A (∝ is a natural number), wherein, when a dot-pattern table corresponding to the gradation-value information is stored in the dot-pattern-table storage unit, the dot pattern selected in said second selection step is recorded by a recording head, and wherein, when a dot-pattern table corresponding to the gradation-value information is not stored in the dot-pattern-table storage unit, the dot patterns corresponding to the predetermined gradation values generated in said dot-pattern generation step are recorded by the recording head.
9. An image recording method for performing recording using a dot pattern corresponding to each gradation value, based on image data representing each pixel with one of N (N is an integer equal to or larger than 3) gradation values, said method comprising the steps of: a first selection step for selecting one dot-pattern table based on gradation-value information of the pixel of the image data and position information of the pixel, from a dot-pattern-table storage unit for storing X (N>X, X is a natural number) dot-pattern tables, each having a plurality of different dot patterns, corresponding to X gradation values provided at intervals of every other gradation level; a second selection step for selecting one dot pattern based on position information of the pixel, from the dot-pattern table selected in said first selection step; and a dot-pattern interpolation step for generating dot patterns corresponding to (N−X) predetermined gradation values, based on a dot pattern within a dot-pattern table corresponding to a gradation value larger than a corresponding one of the predetermined gradation values by one, and a dot pattern within a dot-pattern table corresponding to a gradation value smaller than the corresponding one of the predetermined gradation values by one, wherein the dot-pattern table is a two-dimensional table expanding in a first direction corresponding to a direction of arrangement of nozzles of a recording head and in a second direction different from the first direction, wherein a number of cells L within the dot-pattern table in the first direction and a number of nozzles A of the recording head have a relationship of L=∝×A (∝ is a natural number), wherein, when a dot-pattern table corresponding to the gradation-value information is stored in the dot-pattern-table storage unit, the dot pattern selected in said second selection step is recorded by a recording head, and wherein, when a dot-pattern table corresponding to the gradation-value information is not stored in the dot-pattern-table storage unit, the dot patterns corresponding to the predetermined gradation values generated in said dot-pattern interpolation step are recorded by the recording head.
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June 5, 2000
October 31, 2006
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